Shelf structure for refrigeration



United States Patent Filed Jan. 8, 1965, Ser. No. 424,244 4 Claims. (Cl. 62256) This invention generally relates to the supporting shelves of a refrigerated cabinet having an unimpeded front access opening. The invention is tobe used, more.

particularly, in connection with cabinets having compartmentalized shelf structures where refrigerated air is moved vertically through ashelf space between two adjacent shelf structures. The invention involves an improved type of shelf structure which will reduce the amount of warm room air normally aspirated into the refrigerated system of conventional cabinets.

The present invention is of particular advantage in a system as shown and described in United States Letters Patent No. 3,090,211, which relates to a refrigerating shelf structure comprised of compartmentalized shelf structures, each shelf structure having lower and upper perforated surfaces that allow the passage of air to and from lower and upper compartments, each compartment being connected to a pair of air ducts. The upper compartment of each shelf communicates with an air duct into which refrigerated air is supplied under static pressure. The lower compartment of each shelf structure communicates with an air duct having a vacuum pressure applied thereto for exhausting air from each lower compartment, and the pressure of each lower compartment is maintained below that of the atmosphere surrounding the refrigerated cabinet. In operation, refrigerated air is moved into the air duct that communicates with the upper compartment of each shelf structure, and the air is expelled from these compartments into the spaces between adjacent shelf structures. Simultaneously, air within the spaces between shelves is Withdrawn vertically into the lower compartments and their connecting air du'ct for recycling through a refrigeration coil. While the above described apparatus and refrigeration system may be operated successfully and, produce adequate refrigeration of items stored .on' the shelves, ,under' certain operating conditions, especially when the vertical distance between shelves is great, it, isdifficult to maintain a desired temperature near the peripheral edges of the shelves. may be aspirated into therefrigeration system where it condenses on the refrigeration coil, thercby.requiring frequent defrosting.

- .Previous attempts to regulate the air temperature at 3,232,072 Patented Feb. 1, 1966 ing warm air drawn into the system it is only the cold air barrier itself which is aspirated by the block of upward moving air.

This invention more particularly involves the use of compartmentalized shelf structures having upper and lower air compartments separated by an imperforate member, the upper and lower surfaces of each shelf structure being perforated throughout. Each perforation in,

the upper surface, and those perforations formed inthe lower surface along the front edge of the shelf, provide fluid communication between the upper air compartment and the upper surface and lower front edge of the shelf structure. All other perforations in the lower surface the refrigerated air which is placed under static pressure in the upper compartment is expelled downward through the perforations formed in the lower surface along the front edge of the shelf structure, although the main portion of the refrigerated air is expelled through perforations in the upper surface as to form a block ofv moving air that refrigerates a superjacent shelf space. The portion of the refrigerated air that is expelled downwardly increases the cold air barrier in the critical region near the front of the shelf, and after its downward movement has been arrested by the opposing force of the upward moving refrigerated air, the arrested cold'air'is aspirated back into the system.

In view of the above brief description, it will be apparent that a principal object of this invention is to provide an improved compartmentalized shelf structure 1 structure of the kind described that may be inexpensively In addition, a large amount of warm air the edges of each shelf and to eliminate the aspiration or. any room air have. been generally unsuccessful. A mere increase in the static pressure maintained in each upper compartment has'p'roven'usefulbut usually this results in a great deal of cold air spillage from the front side of the shelf and requires an inordinately large blower. Another solution which has met with moderate success involves providing a greater number of perforations in the upper surface of each shelf along the front edge thereof. This Will increase the mass/rate of refrigerated air moved through the shelf space, however, here again there is an undesirable amount of air spillage from the front side of the shelves.

In brief, the present invention teaches a form of apparatus for blowing a cold air stream downward from the peripheral front edge of a shelf structure while a block of refrigerated air is being moved through a shelf space in the manner previously employed. The downward stream of cold air serves as a barrier to the warm room air on the front side of the cabinet, and rather than havmanufactured and rapidly assembled using a divider member that is essentially imperforate but formed with the front edge portion having perforations extending along the'width thereof, said perforations'allowing fluid communication between an upper air compartment and perforations formed in the lower surface of theshelf.

Other objects of this invention will become apparent in view of the following detailed description and the accompanying drawings.

In the drawings forming a part of this application and which like parts are identified by like reference numerals throughout the same, 'FIG. 1 is a broken view of an open front access cabinet having ,a pair of shelf structures shown in vertical section and constructed in a preferred manner that is contemplated by this invention, said view also showing related refrigeration apparatus and connecting duct work for moving refrigerated air between shelf structures}; FIG. '2" is an enlarged detailof thefront portion of-a shelf structure as shown in FIG. 1; and

FIG. 3 is a perspective view of a portion of the divider member employed in the construction of each shelf structure.

Referring to FIG. 1 of the drawings, there is shown a refrigeration system that is essentially the same as that described in United States Letters Patent No. 3,090,211. In general, the system comprises a plurality of shelves 10 having upper and lower compartments 11 and 12, each shelf being supported from a pair of horizontally spaced air ducts 13 and 14. Each upper compartment 11 fluidly communicates with the air duct 13, and each of lower air compartment 12 communicates with air duct 14. (The air ducts 13 and 14 shown in FIG. 1 are located one in front of the other, and for this reason portions of each air duct have been broken away and illustrated in section to show fluid communication between the air ducts and the upper and lower air compartments of the shelves 10.) A refrigeration coil 15, located within a sealed rear compartment 16, refrigerates air that is circulated between shelves by means of Ciraco type blowers 17 and 18. Blower 17' draws air through refrigeration coil forcing the air into air duct 13 and compartments 11 of each shelf 10. Blower 18, on the other hand, communicates with air duct 14 and each of the lower compartments 12. Accordinglyfrefrigerated air is moved through the space between shelves 10 in an upward direction and as the air is drawn into the lower air compartments under subatmospheric pressure, it is recycled through the refrigeration coil and returned to the compartments 11 where the pressure is maintained at a static pressure well above atmospheric pressure.

This invention is more particularly directed to the construction of the shelves 10 that allows a small amount of refrigerated air in compartments 11 to be ejected downyvardly, details of this construction being shown in FIGS. 2 and 3.

f Each of the shelves 10 are compartmentalized into upper and lower air compartments by means of a divider having an imperforate portion 21 and a front edge portion 22 formed withopenings or perforations 23. Referring to FIG. 2, front edge portion 22 is offset below the imperforate portion 21, and the bottom surface of the front portion is positioned into abutting contact with the interior lower surface of a lower wall 24 that forms part of the shelf structure. Each of the openings 23 provides fluid communication between the upper air compartment 11 and openings 25 formed in lower wall 24. For manufacturing purposes shelf structures 10 may be completely assembled with divider member 20 before openings 23 are formed in front edge portion 22. Then, after assembly, openings 23 are drilled while using openings 25 of lower wall member 24 as a guide.

, The abutting, surface contact between front edge portion 22 and lower wall 24 may suffice as a seal preventing air leakage between the upper and lower compartments. Nevertheless, a more effective seal is obtained with an O-ring strip 26 that is mounted or disposed in a concave surface formed in the bottom of divider 20.

It will be apparent that divider 20- may be inexpensively manufactured of plastic material using conventional molding procedures. Moreover, the increased size of the upper air compartment by reason of the offset formation of front, edge portion 22 increases the reservoir of. pres.- surized air, thereby maintaining the desired static pressure near the peripheral edge of the shelf despite the increase in air openings over those normally used. Failing to provide an increased reservoir space would produce a much greater pressure drop than is obtained with the embodiment shown and described. It will also be apparent that an abnormal pressure drop would greatly reduce the effectiveness of both the downward movement 4. of air ejected 'through'openings 23 and 25 and the vertical upward movement of air ejected through perforations 28 formed in upper wall 29 of the shelf structure.

Although a preferred embodiment of this invention has been illustrated and described, it is to be understood that various changes may be made without departing from the spirit of the invention or the scope of the attached claims, and each of such changes is contemplated.

Having thus described my invention, what I claim and desire to secure by Letters Patent is: 1. In apparatus of the kind described, a compartmentalized shelf structure having upper and lower air compartments separated by an imperforate member, the upper and lower surfaces of said shelf structure being perforated throughout, each perforation in said upper surface and those perforations formed along the front edge in the lower surface providing fluid communication between the upper air compartment and the exterior of the shelf structure, all other perforations in the lower surface providing communication with the lower air compartment; means for moving refrigerated air into said upper compartment and placing said air under static pressure; and a vacuum means for producing subatmospheric air pressure in said lower compartment.

2. The compartmentalized shelf structure of claim 1 wherein said imperforate member is formed integrally with a front edge portion having perforations extending longitudinally thereof, said perforations allowing fluid communication between the upper air compartment and those perforations formed in the lower surface along the front edge of the shelf structure, and means for producing an air seal between said front edge portion and the lower air compartment.

3. The compartmentalized shelf structure of claim 2 wherein the front edge portion is offset at a level below the imperforate member, said front edge portion being positioned in abutting contact with the interior lower surface of said shelf structure.

4. The compartmentalized shelf structure of claim 2 wherein said imperforate member is further formed with a concave surface portionin a region between said front edge portion and the lower air compartment, said means for producingan air seal comprising a resilient strip dis posed within the curvature of said concave surface portion and held in engagement with the interior lower surface of said shelf structure.

References Cited by the Examiner UNITED STATES. PATENTS WILLIAM J. WYE, Primary Examiner, 

1. IN APPARATUS OF THE KINE DESCRIBED, A COMPARTMENTALIZED SHELF STRUCTURE HAVING UPPER AND LOWER AIR COMPARTMENTS SEPARATED BY AN IMPERFORATE MEMBER, THE UPPER AND LOWER SURFACES OF SAID SHELF STRUCTURE BEING PERFORATED THROUGHOUT, EACH PERFORATION IN SAID UPPER SURFACE AND THOSE PERFORATIONS FORMED ALONG THE FRONT EDGE IN THE LOWER SURFACE PROVIDING FLUID COMMUNICATION BETWEEN THE UPPER AIR COMPARTMENT AND THE EXTERIOR OF THE SHELF STRUCTURE, ALL OTHER PERFORATIONS IN THE LOWER SURFACE PROVIDING COMMUNICATION WITH THE LOWER AIR COMPARTMENT; MEANS FOR MOVING REFRIGERATED AIR INTO SAID UPPER COMPARTMENT AND PLACING SAID AIR UNDER STATIC PRESSURE; AND A VACUUM MEANS FOR PRODUCING SUBATMOSPHERIC AIR PRESSURE IN SAID LOWER COMPARTMENT. 